1. Field of the Invention
The present invention relates to an optical disc device capable of reproducing a two-wavelength two-layer disc configured by a first recording layer responding to a laser light of a first wavelength and a second recording layer responding to a laser light of a second wavelength longer than the first wavelength arranged in sequence from the back side when seen from the laser light entering side and so that the first recording layer is not optically detected when the laser light of the second wavelength is used; and a disc determining method suitably used for such a device.
2. Description of the Related Art
Presently, standardization of the next generation DVD (Digital Versatile Disc) using a blue laser light having a wavelength of about 405 nm is being forwarded. In such standardization, consideration is made on arranging two recording layers for the blue laser light (hereinafter referred to as “HDDVD layer”) in the direction of the disc thickness. Further, consideration is made on arranging the HDDVD layer and the recording layer for the red laser light (hereinafter referred to as “DVD layer”) in the direction of the disc thickness.
In the next generation DVD (hereinafter referred to as “hybrid HDDVD”) in which the HDDVD layer and the DVD layer are arranged in the direction of disc thickness, the DVD layer is arranged on the near side and the HDDVD layer is arranged on the back side when seen from the laser light entering side. The HDDVD layer is formed with a material that cannot be optically detected by the red laser light. Further, the same format as that for the existing DVD is applied to the DVD layer.
Japanese Laid-Open Patent Publication No. 2003-346348 discloses an optical disc including two recording layers and a driving device thereof.
Since the DVD layer in the hybrid HDDVD has the same format as the existing DVD, as described above, reading of data is performed as if a DVD were loaded when the drawing operation during recordation/reproduction is performed from the DVD layer on the near side. Since information indicating that the HDDVD layer additionally exists is not recorded on the DVD layer, the hybrid HDDVD cannot be appropriately determined only from the data read from the disc at the driving side. Thus, the optical disc device requires a means for making an appropriate determination when the hybrid HDDVD is loaded.
However, since the HDDVD layer is not optically detected by the red laser light, as mentioned above, it is difficult to determine the hybrid HDDVD using the red laser light. Although the blue laser light is preferably used for disc determination, the red laser light used for DVD is preferably set as the priority laser light in reproduction rather than the blue laser light taking into account that DVDs are already commercialized, so that a rapid transition to the reproducing operation is achieved when the DVD is loaded.